Wireless sensor networks are becoming more and more common in industrial plants. This naturally gives the advantage of communication from and/or to sensors, or other device, without the need for wires. Consequently, the networks are easier to deploy, maintain and eventually, de-commission.
However, when multiple wireless networks are used, interference between networks may cause problems. This interference may result in packets not being received properly, which may require re-transmission of any packets which have been subject to interference. This will delay the communication and will also use more energy, which is particularly problematic when the sensors are battery powered, which is frequently the case with industrial wireless sensor networks.
The United States patent application with publication number US2006/0094371 describes automatic channel selection in a wireless access point. An automatic channel selection (ACS) process enables an access point to determine a best channel available, i.e., the channel with a least amount of interference, for its operation. When ACS is enabled, the access point scans frequencies for all neighboring access points and their signal strengths. Based on this data, the access point then determines which frequency is least likely to be interfered with by these other access points. The access point switches itself to this frequency and begins operation. This rudimentary approach may work in situation where only the aspect of frequency is used to separate channels. However, the automatic channel selection described can not be used for situations where the same frequency is used across several access points.
US-2002/136233 presents a system and methods for coordinating transmissions in a wireless network wherein a plurality of frequency-overlapping protocols are used to exchange information between devices. In this system, a coordination point device integrates a monitoring functionality to identify impending data collisions between the frequency-overlapping protocols. The coordination point device further identifies quality of service parameters to determine if the protocols are operating within desirable ranges. Moderation one or more of the protocols is then performed to avoid data collisions arising from overlapping transmissions between the protocols while maintaining data throughput within acceptable ranges.
US 2002/173272 presents a device and various network configurations for monitoring, moderating, and/or coordinating wireless transmission traffic in a wireless communication network where overlapping communication frequencies coexist to significantly reduce or avoid interference caused by signal collisions.